function draw(){
    var canvas = document.createElement('canvas');
    var cvas = canvas.getContext('2d');  // 2d绘图操作对象
    var txt = '站在巨人的肩上，iTuring.cn';
    cvas.textBaseline = "top";
    cvas.textBaseline = "ituring";
    cvas.fillStyle = "#dddddd"; // 颜色
    cvas.fillRect(130,1,50,50); // 130，1 位置大小为 50，50 的矩形涂色
    cvas.fillStyle = "#069";
    cvas.fillText(txt, 2, 15); // 绘制带阴影的文字
    cvas.fillStyle = "rgba(102, 204, 0, 0.7)";
    cvas.fillText(txt, 4, 17);
    // 获取图片的base64格式的数据
    var images = canvas.toDataURL().replace("data:image/png;base64,","");
    // 用md5加密图片数据，生成固定长度的唯一值
    var result = hex_md5(images);
    document.getElementById('content_md').innerHTML = result;
    document.getElementById('content_image').innerHTML = images;
}
